#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>

struct Task
{
    unsigned uid;
    int gid_count;
    unsigned *gids;
};

static int isuser(const struct stat *stb, const struct Task *task) {
    if (stb->st_uid == task->uid) {
        return 1;
    }
    return 0;
}

static int isgrp (const struct stat *stb, const struct Task *task) {
    for (int i = 0; i < task->gid_count; i++) {
        if (task->gids[i] == stb->st_gid) {
            return 1;
        }
    }
    return 0;
}

enum masks
{
    USER = 0700,
    GROUP = 0070,
    OTHER = 0007,
    U_OFFSET = 6,
    G_OFFSET = 3
};

enum { permissions = 3 };

int myaccess(const struct stat *stb, const struct Task *task, int access) {
    if (task->uid == 0) {
        return 1;
    }
    int mode;
    if (isuser(stb, task)) {
        mode = stb->st_mode & USER;
        mode >>= U_OFFSET;
        if (access != mode) {
            return 0;
        }
    } else if (isgrp(stb, task)) {
        mode = stb->st_mode & GROUP;
        mode >>= G_OFFSET;
        if (access != mode) {
            return 0;
        }
    } else {
        mode = stb->st_mode & OTHER;
        if (access != mode) {
            return 0;
        }
    }
    return 1;
}